Field of the Invention
This disclosure relates to modulating devices for optical communication.
Description of the Related Art
The growth in social networking, e-commerce, cloud computing, data streaming, etc. is causing an explosive growth in global data traffic. Handling this growth requires high capacity networks that can carry a large amount of data traffic over large distances while maintaining signal quality. One way to handle such growth is through the use of optical communication systems operating at relatively high data rates, including data rates beyond 1.0 Gbits/s, for example 2.5 Gbits/s, 10 Gbits/s, 20 Gbits/s. 40 Gbits/s, 100 Gbits/s, 128 Gbits/s, and 256 Gbits/s. Increased data rates can be achieved by direct optical modulation, dense wavelength division multiplexing (DWDM), optical frequency division multiplexing (OFDM) or other methods. Existing optical communication systems typically rely on some form of on/offkeying (OOK) as a modulation format, such as, for example, non-return to zero (NRZ) or return-to-zero (RZ) modulation formats. Spectral inefficiencies in existing systems can lead to undesirable effects including interference between channels. There is a need for optical communication systems having improved spectral efficiency.